1. Field of the Invention
The present invention generally relates to data processing and more particularly to a mechanism for process migration on a massively parallel computer system.
2. Description of the Related Art
Powerful computers may be designed as highly parallel systems where the processing activity of hundreds, if not thousands, of processors (CPUs) are coordinated to perform computing tasks. These systems are highly useful for a broad variety of applications including, financial modeling, hydrodynamics, quantum chemistry, astronomy, weather modeling and prediction, geological modeling, prime number factoring, image processing (e.g., CGI animations and rendering), to name but a few examples.
For example, one family of parallel computing systems has been (and continues to be) developed by International Business Machines (IBM) under the name Blue Gene®. The Blue Gene/L architecture provides a scalable, parallel computer that may be configured with a maximum of 65,536 (216) compute nodes. Each compute node includes a single application specific integrated circuit (ASIC) with 2 CPU's and memory. The Blue Gene/L architecture has been successful and on Oct. 27, 2005, IBM announced that a Blue Gene/L system had reached an operational speed of 280.6 teraflops (280.6 trillion floating-point operations per second), making it the fastest computer in the world at that time. Further, as of June 2005, Blue Gene/L installations at various sites world-wide were among five out of the ten top most powerful computers in the world.
The compute nodes in a parallel system typically communicate with one another over multiple communication networks. For example, the compute nodes of a Blue Gene/L system are interconnected using five specialized networks. The primary communication strategy for the Blue Gene/L system is message passing over a torus network (i.e., a set of point-to-point links between pairs of nodes). The torus network allows application programs developed for parallel processing systems to use high level interfaces such as Message Passing Interface (MPI) and Aggregate Remote Memory Copy Interface (ARMCI) to perform computing tasks and distribute data among a set of compute nodes. Of course, other message passing interfaces have been (and are being) developed. Other parallel architectures also use MPI and ARMCI for data communication between compute nodes connected via a variety of network topologies. Typically, MPI messages are encapsulated in a set of packets which are transmitted from a source node to a destination node over a communications network (e.g., the torus network of a Blue Gene system).
Another network connecting compute nodes of a Blue Gene system is a global combining network, in which the nodes are connected into a binary tree. Each compute node has a parent and at most two children. In a Blue Gene system, the combining tree and the torus networks are independent of one another, i.e., they do not share network resources such as links or packet injection FIFOs.
Accordingly, embodiments of the present invention provide mechanisms for process migration on a massively parallel computer system.